U.S. patent number 7,319,836 [Application Number 11/608,139] was granted by the patent office on 2008-01-15 for image forming device.
This patent grant is currently assigned to Murata Kikai Kabushiki Kaisha. Invention is credited to Yoshiharu Kuroda.
United States Patent |
7,319,836 |
Kuroda |
January 15, 2008 |
Image forming device
Abstract
An image forming device includes a device frame and a
photoconductive drum. The device frame includes a driving device, a
driving gear that transmits a driving force from the driving
device, and an urging member that supports the driving gear in a
manner capable of moving along a moving direction of a
photoconductive drum and urges the driving gear in an opposite
direction from a direction in which the photoconductive drum is
inserted. The photoconductive drum is inserted in the device frame
and includes a driven gear to be engaged with the driving gear.
Inventors: |
Kuroda; Yoshiharu (Kyoto,
JP) |
Assignee: |
Murata Kikai Kabushiki Kaisha
(Kyoto, JP)
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Family
ID: |
34797791 |
Appl.
No.: |
11/608,139 |
Filed: |
December 7, 2006 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20070098444 A1 |
May 3, 2007 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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11033235 |
Jan 11, 2005 |
7173409 |
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Foreign Application Priority Data
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Jan 26, 2004 [JP] |
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2004-016512 |
Nov 10, 2004 [JP] |
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2004-325866 |
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Current U.S.
Class: |
399/167;
399/116 |
Current CPC
Class: |
G03G
15/757 (20130101) |
Current International
Class: |
G03G
15/00 (20060101) |
Field of
Search: |
;399/167,159,116 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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08-115009 |
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May 1996 |
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JP |
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2002304030 |
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Oct 2002 |
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JP |
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Primary Examiner: Lee; Susan
Attorney, Agent or Firm: Hogan & Hartson LLP
Parent Case Text
RELATED APPLICATIONS
This is a continuation of application Ser. No. 11/033,235 filed on
Jan. 11, 2005 now U.S. Pat. No. 7,173,409, which claims priority
under 35 USC 119 in Japanese Patent Application Nos. 2004-016512,
filed on Jan. 26, 2004 and 2004-325866 filed on Nov. 10, 2004,
which applications are incorporated by reference in their
entireties.
Claims
The invention claimed is:
1. An image forming device comprising: a device frame which
includes: a driving device, and a driving gear that transmits a
driving force from the device; and a photoconductive drum which is
inserted in the device frame and includes a driven gear to be
engaged with the driving gear, wherein after the photoconductive
drum is inserted in the device frame, by driving the driving device
and slightly rotating the driving gear, the driving gear engages
with the driven gear, and wherein the driving gear is slightly
rotated at an initializing step of the image forming device.
2. The image forming device according to claim 1, wherein the
driving gear is movable along a moving direction of the
photoconductive drum, and the device frame includes an urging
member that urges the driving gear in an opposite direction from a
direction in which the photoconductive drum is inserted.
3. The image forming device according to claim 2, wherein when
inserting the photoconductive drum into the device frame, in case a
tooth of the driving gear and a tooth of the driven gear contact
with one another, by inserting the photoconductive drum further
into the device frame, the driving gear is pushed in against an
urging force of the urging member.
4. The image forming device according to claim 2, wherein the
driving device is a motor fixed on a frame of the device frame, and
the driving gear is mounted on an output shaft of the motor in a
manner capable of sliding in an axial direction of the output
shaft.
5. The image forming device according to claim 4, wherein a key
extending over approximately an entire length of the output shaft
is fixed on the output shaft, and the driving gear can rotate with
the output shaft by the key regardless of where the driving gear is
located on the output shaft.
6. The image forming device according to claim 4, wherein the
urging member is a coil spring and would around the output shaft
between the driving gear and the frame.
7. The image forming device according to claim 4, wherein a shaft
hole is formed through the frame, and under a state in which the
photoconductive drum is inserted in the device frame, a shaft of
the photoconductive drum is inserted through the shaft hole.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrophotographic image
forming device. In particular, the present invention relates to an
image forming device which can transmit a driving force by engaging
a driving gear of a device frame and a driven gear of a
photoconductive drum after inserting the photoconductive drum into
the device frame.
2. Description of Related Art
In a conventional image forming device which forms an image by
transferring a toner image onto paper, when a photoconductive drum
is inserted into a device frame, a driven gear of the
photoconductive drum is engaged with a driving gear which receives
a driving force from a driving source of the device frame. In such
a conventional image forming device, when the photoconductive drum
is a unit and the photoconductive drum unit is inserted into the
device frame, or when the photoconductive drum is inserted into the
device frame, a driving force is transmitted from the driving
source of the device frame to the photoconductive drum.
However, just by inserting the photoconductive drum unit or the
photoconductive drum into the device frame, there are cases in
which the driving gear and the driven gear are not engaged
satisfactorily with one another. That is, there are cases in which
a tooth of the driving gear of the device frame and a tooth of the
driven gear of the photoconductive drum contact with one another (a
tooth contact is generated) and a normal engaged state cannot be
established.
However, according to the present invention, when the
photoconductive drum is inserted into the device frame, even in
case the tooth contact is generated, an engaged state of the gears
can be normalized easily.
SUMMARY OF THE INVENTION
According to an aspect of the present invention, an image forming
device includes a device frame and a photoconductive drum which is
inserted into the device frame. The device frame includes a driving
device, a driving gear for transmitting a driving force from the
driving device and an urging member. The urging member supports the
driving gear in a manner capable of moving along a moving direction
of the photoconductive drum. The urging member urges the driving
gear in an opposite direction from a direction in which the
photoconductive drum is inserted.
According to an aspect of the present invention, when inserting the
photoconductive drum into the device frame, in case a tooth of the
driving gear and a tooth of the driven gear make contact with one
another, the driving gear is preferable to be pushed in against the
urging force of the urging member by continuing to insert the
photoconductive drum into the device frame.
According to an aspect of the present invention, after the
photoconductive drum is inserted into the device frame, it is
preferable that the driving source is driven to rotate the driving
gear slightly.
According to an aspect of the present invention, the driving device
is preferable to be a motor fixed on a frame of the device frame.
The driving gear is preferable to be mounted on an output shaft of
the motor in a manner capable of sliding in an axial direction of
the output shaft.
According to an aspect of the present invention, it is preferable
that a key extending over approximately an entire length of the
output shaft is fixed on the output shaft and the driving gear can
be rotated with the output shaft by the key regardless of where the
driving gear is located on the output shaft.
According to an aspect of the present invention, it is preferable
that the urging member is a coil spring and wound around the output
shaft between the driving gear and the frame.
According to an aspect of the present invention, it is preferable
that a shaft hole is formed through the frame and under a state in
which the photoconductive drum is inserted in the device frame, a
shaft of the photoconductive drum is inserted through the shaft
hole.
According to the present invention, the driving gear is provided
movable in an axial direction via the urging member. Therefore,
even when a tooth of the driven gear of the photoconductive drum
and a tooth of the driving gear make contact with one another, the
tooth contact does not influence the insertion of the
photoconductive drum. When the photoconductive drum is inserted, in
case both of the gears are not engaged with one another, just by
rotating the driving gear slightly, the tooth contacting state is
resolved and both of the gears are engaged with one another
normally. As a result, a driving force can be transmitted
preferably to the photoconductive drum.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 shows an image forming device according to an embodiment of
the present invention.
FIG. 2 shows a state in which a driven gear of a photoconductive
drum and a driving gear of a device frame are engaged normally with
one another.
FIG. 3 is a perspective view showing a state in which a tooth of
the driven gear of the photoconductive drum and a tooth of the
driving gear of the device frame are making contact with one
another.
FIG. 4 is a cross-sectional view of FIG. 3.
FIG. 5 shows a movement when inserting the photoconductive drum
into the device frame.
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described. Further,
the embodiments to be described below are preferable specific
examples for implementing the present invention. Therefore, there
are various technical limitations in the description. However,
unless explicitly stated in the following description to limit the
present invention, the present invention shall not be limited to
the embodiments.
An image forming device 1 according to an embodiment of the present
invention will be described. The image forming device 1 is an
electrophotographic image forming device which transfers and fixes
a toner image onto paper. The image forming device 1 can be applied
to a facsimile machine, a printer device, a copying machine or a
Multi Function Peripheral (MFP) having multiple functions of these
machines. The image forming device 1 includes a printing unit 10
provided in a device frame 2. The printing unit 10 prints an image
onto the paper by using an electrophotographic method. An image
scanning device 30 and an Automatic Document Feeder (ADF) 40 are
provided in an upper part of the device frame 2. In the embodiment
to be described below, the structure of the image scanning device
20 is omitted. Therefore, a drive transmitting mechanism to a
photoconductive drum 11 inserted in the device frame 2 will be
described mainly.
In the image forming device 1 shown in FIG. 1, at least one paper
feed cassette 4 is provided in a paper feed unit 3 provided in a
lower part of the device frame 2. The paper is fed from the paper
feed cassette 4 by a paper feed roller 5. The fed paper is fed into
a paper transportation path 6 and transported toward the printing
unit 10. Further, a plurality of paper feed cassettes 4 can be set
in the paper feed unit 3. A paper feed cassette 4 storing paper of
a necessary size can be selected. Then, the paper can be fed from
the selected paper feed cassette 4. A plurality of transportation
roller devices 7 and 7a are disposed along the paper transportation
path 6 with a prescribed interval between one another.
A leading edge of the paper fed from the paper feed cassette 4 hits
against the transportation roller device 7 upstream of the printing
unit 10 in the paper transportation path 6. Under this state, an
additional feeding force is applied to the paper by the
transportation roller device 7a located further upstream in the
paper transportation path 6 and the paper is looped. When the
leading edge of the paper enters into a nip of the transportation
roller device 7, the leading edge of the paper is arranged and the
paper stops under this state. The transportation roller device 7 is
driven in accordance with a timing in which a toner image is formed
on the photoconductive drum 11. The paper is transported toward a
nipped part between the photoconductive drum 11 and a transfer
roller 16. Under a state in which the paper is nipped between the
photoconductive drum 11 and the transfer roller 16, when a transfer
voltage is impressed to the transfer roller 16, the toner image is
transferred onto the paper.
The printing unit 10 includes the photoconductive drum 11 like a
general electrophotographic device. A charging member 14, a writing
member 15, a developing device 12, the transfer roller 16 and a
cleaning device 17 are disposed around the photoconductive drum 11
along a rotational direction of the photoconductive drum 11. The
developing device 12 is provided downstream of the writing member
14. A developing roller 13 exposed to an outer side of the printing
unit 10 makes contact with the photoconductive drum 11. A surface
of the photoconductive drum 11 is charged uniformly by the charging
member 14. By irradiating a light of an image by the writing member
15, an electrostatic latent image is formed on the surface of the
photoconductive drum 11. A toner is supplied from the developing
roller 13 and adhered onto the electrostatic latent image.
Accordingly, a toner image as a visible image is formed.
As described above, when the paper is transported while being
nipped between the photoconductive drum 11 and the transfer roller
16, the toner image is transferred onto the paper by the transfer
roller 16 to which a voltage of a prescribed value is impressed.
When the paper passes a fixing device 8, heat and pressure are
applied to the toner image carried on the paper and the toner image
is fixed onto the paper. Then, the paper is discharged onto a
discharge tray (not shown) by a discharge roller device 9. After
transferring the toner image formed on the photoconductive drum 11
onto the paper, the toner remaining on the photoconductive drum 11
without being transferred is scraped off by a blade 18 of the
cleaning device 17. The scraped off toner is transported toward a
waste toner box (not shown).
In the above-described image forming device 1, in a small-sized
printer or the like, the photoconductive drum 11 provided at the
printing unit 10 is designed capable of carrying out an image
forming process for approximately several thousands sheets.
Therefore, when a number of printed sheets exceeds a designated
number of sheets, a message indicating a replacement of the
photoconductive drum 11 is displayed on a display unit (not shown).
There are cases in which the photoconductive drum 11 is replaced
solely and cases in which the photoconductive drum 11 is replaced
as a photoconductive drum unit including a peripheral member. In
the present invention, the photoconductive drum 11 can be replaced
solely or as a photoconductive drum unit. In the image forming
device 1 of the present embodiment, when the photoconductive drum
11 is inserted in the device frame 2, a driving gear 24 of a
driving mechanism of the device frame 2 engages with a drum gear 25
as a driven gear of the photoconductive drum 11.
As shown in FIG. 2, a driving device 21 of the device frame 2 is
provided. The drum gear 25 of the photoconductive drum 11 inserted
in the device frame 2 engages with the driving gear 24 of the
driving device 21. To describe in detail, the driving device 21
shown in FIG. 2 is fixed on a frame 20 of the device frame 2. The
driving device 21 includes a motor having a deceleration mechanism.
A tip end of an output shaft 22 of the motor is protruding inward
in the printing unit 10. The driving gear 24 is mounted on the tip
end of the output shaft 22. The driving gear 24 is capable of
sliding along the output shaft 22. The driving gear 24 is urged at
all times toward a tip end of the output shaft 22 by a spring 23 as
an urging member. The spring 23 is wound around the output shaft 22
between the driving gear 24 and the frame 20. A key extending over
an entire length in an axial direction of the output shaft 22 is
fixed on the output shaft 22. Therefore, regardless of where the
driving gear 24 is located on the output shaft 22 in the axial
direction of the output shaft 22, the driving gear 24 can be
rotated by the output shaft 22. Furthermore, the drum gear 25 is
fixed at a position displaced from an image forming region on the
photoconductive drum 11. Further, in the example shown in the
drawing, under a state in which the photoconductive drum 11 is
inserted in the device frame 2, a tip end of a drum shaft 26 of the
photoconductive drum 11 is inserted in a shaft hole of the frame 20
and the photoconductive drum 11 is positioned with respect to the
device frame 2.
When inserting the photoconductive drum 11 into the device frame 2
for replacing or reinserting the photoconductive drum 11, if the
photoconductive drum 11 is simply pushed in along the drum shaft
26, there are cases in which a tooth of the driving gear 24 and a
tooth of the drum gear 25 contact with one another and a preferable
engaged state cannot established. That is, as shown in FIG. 3, a
failure is prone to generate such that the gear teeth contact
(collide) with one another at a tooth contacting part Z. If the
driving gear 24 is fixed on the output shaft 22, the drum gear 25
forcibly pushes the driving gear 24. In this case, when inserting
the photoconductive drum 11, if the photoconductive drum 11 is not
rotated at a prescribed angle at the same time as when pushing in
the photoconductive drum 11, the photoconductive drum 11 may not be
inserted preferably.
To solve the drawback of the above-described tooth contact of the
gears, as shown in FIG. 2, in the image forming device 1 of the
present embodiment, the driving gear 24 of the device frame 2 is
provided movable with respect to the axial direction of the output
shaft 22 and urged by the spring 23 from a rear side of the driving
gear 24. Therefore, when inserting the photoconductive drum 11 into
the printing unit 10, as shown in FIG. 4, the driving gear 24 and
the drum gear 25 collide with one another at the teeth contacting
part Z. However, when the photoconductive drum 11 is pushed further
against the urging force of the spring 23, as shown in FIG. 5, the
driving gear 24 is pushed and recedes to a position shown with a
solid line in the drawing. The photoconductive drum 11 is
maintained at a prescribed operation position under a state in
which the gear teeth are contacting with one another. Under this
state, since the drum gear 25 is not engaged normally with the
driving gear 24, the photoconductive drum 11 cannot rotate
normally.
However, in the image forming device 1 of the present embodiment,
under the state shown with the solid line in FIG. 5, by driving the
driving device 21 and slightly rotating the output shaft 22, the
state in which the gear teeth are pushing one another is resolved.
That is, when the output shaft 22 rotates slightly and the driving
gear 24 and the drum gear 25 are located at a position to be
engaged with one another, the driving gear 24 moves toward the drum
gear 25 by the urging force of the spring 23. When the driving gear
24 moves from the solid line position of FIG. 5 to an imaginary
line position, the driving gear 24 and the drum gear 25 are engaged
completely with one another. Accordingly, the photoconductive drum
11 can be driven by the driving device 21.
As described above, a process for driving the driving device 21 for
a short period of time after setting the photoconductive drum 11 at
the printing unit 10 is preferable to be provided in an
initializing step of the image forming device 1. The initializing
step is a step for confirming whether or not each of the members of
the printing unit 10 is operating normally. That is, in a general
image forming device, after the photoconductive drum 11 is replaced
or after each of the members of the printing unit 10 is reequipped,
in accordance with a control program set in a control device of the
image forming device 1, the photoconductive drum 11 idles just for
a short period of time and a confirmation is carried out in an
initializing operation for confirming that each of the members is
operating normally. Therefore, by using the above-described
operation, the engagement of the gear teeth can be normalized.
Thus, the photoconductive drum 11 can be inserted easily compared
with a conventional image forming device.
The image scanning device 30 provided in the upper part of the
device frame 2 will be described briefly As shown in FIG. 1, a
scanner device 35 which scans an image of an original document in
cooperation with the ADF 40 is provided at a fixed position on an
upper frame 31. As shown in the drawing, the scanner device 35
includes a plurality of mirrors 37, a lens 38 and a Charge Coupled
Device (CCD) 39 as one unit. The scanner device 35 is fixed at a
position corresponding to a platen 32 in proximity to an end part
of the upper frame 31. In the scanner device 35, a light from a
lamp 36 is irradiated on the original document moving while sliding
an image surface against the platen 32. The reflected light is
reflected by the plurality of mirrors 37. The reflected light is
focused by the lens 38 and an image is formed in the CCD 39.
Optical information corresponding to the original document is
obtained as digital information.
The ADF 40 includes a document tray 43 and a discharge tray 44
provided one on the other vertically with a prescribed interval
between one another. The trays 43 and 44 are fixed on the upper
frame 31. The ADF 40 includes a document transportation path 41
which connects the two trays 43 and 44. The document transportation
path 41 is formed in approximately a sideways letter-U shape like a
conventional ADF. The platen 32 is provided at a lower part of a
curved part of the document transportation path 41. While the
original document picked up by a document feeder 42 one sheet at a
time is transported through the document transportation path 41 at
a constant speed, an image scanning process is carried out.
By combining the device frame 2 having the printing unit 10 and the
image scanning device 30 provided in the upper part of the device
frame 2, a MFP having functions of a copying machine and a
facsimile machine can be formed. Without providing the image
scanning device in the upper part of the device frame 2, the device
frame 2 can be used as a printer. The image scanning device
provided in the upper part of the device frame 2 can be formed as a
mechanism which supports both a Flat Bed Scanner (FBS) function and
an ADF function.
* * * * *